lecture notes - government polytechnic, nayagarh

MANUFACTURING TECHNOLOGY

LECTURE NOTES

��

��

��

�

(4th

semester MECHANICAL ENGINEERING)

Prepared By

Soma Dalbehera

Lecturer Mechanical Engineering

GP Nayagarh


��

Total Periods 60

�

��

�

1.0 Tool Materials

1.1 Composition of various tool materials

1.2 Physical properties& uses of such tool materials.

2.0 Cutting Tool 2.1 Cutting action of various hand tools such as Chisel, hack saw blade, dies and reamer

2.2 Turning tool geometry and purpose of tool angle

2.3 Machining process parameters

2.4 Coolant and lubricant in machining purposes

3.0 Lathe Machines

3.1 Construction and working of lathe

• Major components of a lathe and their function

• Operations carried out in a lathe (Turning, thread cutting, taper turning, internal

machining, parting off, facing, knurling)

• Safety measures during machining

3.2 Capstan Lathe

• Difference with respect to engine lathe

• Major components and their function

• Define multiple tool holders

Name of the Course: Diploma in Mech/Auto/ & Other Mechanical Allied Branches

Course code: TH-2 Semester 4th

Total Period: 60 Examination 3 hrs

Theory periods: 4 P/W Class Test: 20

Maximum marks: 100 End Semester

Examination:

80

Sl. No. Topic Periods 01 Tool Materials 04

02 Cutting Tools 06

03 Lathe Machine 08

04 Shaper 06

05 Planning Machine 06

06 Milling Machine 08

07 Slotter 06

08 Grinding 06

09 Internal Machining operations 06

10 Surface finish, lapping 04


3.3 Turret Lathe

• Difference with respect to capstan lathe

• Major components and their function

3.4 Draw the tooling lay out for preparation of a hexagonal bolt & bush

4.0 Shaper Machine

4.1 Potential application areas of a shaper machine

4.2 Major components and their function

4.3 Explain the automatic able feed mechanism

4.4 Explain the construction &working of tool head

4.5 Explain the quick return mechanism through sketch

4.6 State the specification of a shaping machine.

5.0 Planning Machine

5.1 Application area of a planer and its difference with respect to shaper

5.2 Major components and their functions

5.3 The table drive mechanism

5.4 Working of tool and tool support

5.5 Clamping of work through sketch.

6.0 Milling Machine

6.1Types of milling machine and operations performed by them

6.2 Construction & working of simple dividing head, universal dividing

head

6.3 Procedure of simple and compound indexing

6.4 Illustration of different indexing methods

7.0 Slotter

7.1 Major components and their function

7.2 Construction and working of slotter machine

7.3 Tools used in slotter

8.0 Grinding

8.1 Significance of grinding operations

8.2 Manufacturing of grinding wheels

8.3 Criteria for selecting of grinding wheels

8.4 Specification of grinding wheels with example

Working of

• Cylindrical Grinder

• Surface Grinder

• Centreless Grinder

9.0 Internal Machining operations

Classification of drilling machines

9.1 Working of

• Bench drilling machine

• Pillar drilling machine

• Radial drilling machine

9.2 Boring

• Basic Principle of Boring


• Different between Boring and drilling

9.3 Broaching

• Types of Broaching(pull type, push type)

• Advantages of Broaching and applications

10.0 Surface finish, lapping

10.1 Definition of Surface finish

10.2 Description of lapping& explain their specific cutting.


Tool Materials

Chapter-1

Manufacturing technology:

It is defined as a field of study focused on process techniques or

equipments, cost reduction, increased efficiency, enhanced reliability,

security safety and anti-pollution measures are its objects.

Tool Material:

The characteristic of the ideal cutting tool material are-

(a) Hot hardness

(b) Wear resistance

(c) Toughness

(d) Cost and easiness in fabrication


Hot hardness:

The material must remain hander than the the work material at

elevated operating temperatures.

Wear resistances:

The material must withstand excessive were even through the

relative hardness of the tool-work materials changes.

Toughness:

The term toughness actually implies a combination of strength and

ductility. The material must have sufficient toughness to withstand shocks

and vibrations and to prevent breakage.

Cost and easiness in fabrication:

The cost and easiness of fabrication should have within reasonable

limits.

State the composition of various tool material

The cutting tool materials are-:

1. Carbon steels

2. Medium alloy steel

3. High speed steels

4. Stellites

5. Cemented carbides

6. Ceramics

7. Diamonds

8. Abrasives

9. Cubic boron nitride(CBN)


Composition of carbon steels:

Carbon steels contain carbon in amounts ranging fron 0.008 to 1.5%

Composition of medium alloy steel:

The high carbon medium alloy steels have a carbon content akin to

plain carbon steels,but in addition there is ,say up to 5% alloy content

consisting there of tungsten,molybdenum,chromium and vanadium.

Composition of high speed steel:

High speed steel is the general pupose metal for low and medium

cutting speed owing to its soperior three type of high speed steel

1. High tungsten

2. High molybdenum

3. High cobalt

Actually these three named modify as following

1. 18-4-1 high speed steel (T-series)

2. Molybdenum high speed steel(M-series)

3. Cobalt high speed steel

Composition of 18-4-1 high speed steel (T-series)-

This steel containing 18% tungsten, 4% Cr & 1% vanadium, is

considered to be one of the best of all purpose o f tool steel.

Composition of molybdenum high speed steel (M-series):

This steel containing 6% Molybdenum,6%W,4% Cr % & 2%

vanadium.

Composition of cobalt high speed steel:

This is sometimes called super high speed steel. Cobalt is added from

2 to 15% to increase of the steel containt 20% tungsten 4%cr, 2% v & 12%

cobalt.


Composition of satellites:

Satellites are the trade name of a nonferrous cost alloy cobalt,

chromium and tungsten. The ranges of elements in these alloys is40 to 48%,

30 to 35% Cr & 12 to 19% tungsten.

Composition of cemented carbides:

A typical analysis of a carbide suitable for steel machining is 82%

tungsten carbide,10% titanium carbide and 8% cobalt.

Composition of ceramics:

The latest development in the metal cutting tools use Al oxide

generally referred to as ceramics

Tools are made by composing aluminium oxide powder in a mould

at about 280 kg/cm2 or more.

Composition of diamonds:

The diamonds are used for cutting tools are industrial diamonds,

which are naturally occurring diamonds.

Composition of abrasive:

Abrasive grains in various forms, loose, bonded into wheels and

extended in papers and story and extended in paper s and cloths find wide

application in industry. They are mainly used for grinding harder materials

and where a superior finish is desired on hardened or unhardened materials.

Composition of Cubic Boron Nitride (CBN):

This material consisting atoms of boron and nitrogen is considered

as the hardest tool material available.


Physical properties and user of different types of tool material:

The various type of tool materials are:

1. Carbon steel

2. Medium alloy steel

3. High speed steel

4. Cast alloy satellites

5. Cemented carbide tool material

6. oxide or ceramic tool material

7. diamonds

8. abrasives

9. cubic boron nitride(CBN)

Carbon steel:

Properties

I. low hot hardness

II. poor harden ability

III. can be withstand cutting temperature 2000c

IV. carbon tool steel are harder than many hss

uses: It can be used most economically under these condition.

(a) The carbon steels are used for making certain taps and drills.

(b) For making wood working tools

Medium alloy steel:

Properties

i) Better hardenability.

ii) Higher wear resistance.

iii) Higher hardness.

Uses

i) Used for making drills

ii) Used for making taps, etc

iii) It can aut effectively up to temperature 250 to 3000c.


High speed steel (HSS):

Properties

i) High hot hardness

ii) Cutting tools retain the cutting ability upto 6000 c.

iii) High wear resistance.

iv) The hardenability is good.

Uses

i) Drills

ii) Broaches

iii) Milling cutters

iv) Lathe cutting tools

v) Taps,etc.

Cast alloy satellite:

Properties:

i) Material is not so hard at room temperature

ii) Hardness above 10000F is greater then high speed steels.

iii) Hat hardness is higher then H.S.S at higher temprature.

iv) This material is very brittle

Uses

These material are used extensively in some non metal cutting

application such as rubbers, plastics.

Cemented Carbide:

Properties:

i) High hardness

ii) High heat resistance

iii) High wear resistance

iv) High hot hardness upto a temp. of 9000 c

v) Low specific heat


Uses:

These tool materials are used for machining cast iron, alloy steels.

Oxides ceramic tool material:

Properties:

I) The ceramic has extremely high compressive strength. It is

quietly brittle.

II) Heat conductivity is very low. So generally no coolant is required

while machining

III) The ceramic tools can retain strength and hardness upto 12000c.

Uses:

These tool materials are used for turning boring, etc operations at

high speed.

Diamonds are cutting tools:

Properties:

i) It has a low co-efficient of friction

ii) Hardness of the diamond is incompressible.

Uses:

Diamonds are suitable for cutting very hard material such as glass,

plastics, ceramics.

Abrasive:

Uses:

For most grinding operations there are two kinds of abrasives in

general use namely aluminium oxide and silicon carbide. The aluminium

oxide abrasive are used for grinding all high tensile materials, where as

Silicon Carbide abrasives are more stable for low tensile materials


Cutting Tools

Chapter-2

Cutting tools:

In machining a cutting tool or cutter is any tool which is used to

remove the material from the W/P by means of shear difference

Cutting tool must be made of a material harder than the material which is to

be cut and the tool must be to withstand the heat generated in the metal

cutting process

The angle of cutting facer is also important, also the tool must have a

specific geometry and clearance angles designed so that the cutting edge can

contact the W/P surface .

MANUFA

Single point cutting

This type of

wide application of l

Multi point cutting to

This type cu

employed for wide

cutters etc.


ng tool

f cutting tools have only one cutting edge. These

f lathe, shaper planner, slitter, boring M/C

tools

cutting tools have more than cutting edge. T

de application in twist drills, Reamers, tapes,

ese used for

These are

s, milling

MANUFA

Cutting action of ha

Chisel:

A chisel is a

on its end, for carvin

hand with the help o

In used the

motion.

The driving

using a hammer.

In industrial

into the material to b

Chisel is emp

In wood & st

trimming.

In metal work

Cold chisel:


hand tools

a hand cutting tools which is shaped cutting edge

ving, cutting a hard material such as wood, stone,

of mechanical power.

e chisels are forced in to the material to linea

g forced into the material may be manually ap

al use, a hydraulic ram or falling weight drives

o be cut .

ployed to use in wood work, metal working etc.

stone working used for carving, cutting, shaving,

orking process chisel use divided into two categori

ge of blade

e, metal by

ear relative

applied by

s the chisel

, shaping,

ories:

MANUFA

It is made of

Use for cuttin

Used to remo

not necessary or whe

Hot chisel:

A hot chisel i

sustain the metal.

Used to smoo

Hacksaw blade

metal.

Hacksaw bled

They can also

There are hea


of from tempered steel.

ting cold metal.

ove waste metal in the situation where a smooth

hen other tools such as file, hacksaws cannot be u

l is used to cut metal that has been heated in a forc

ooth the metals.

led is a fine toothed saw, originally principally for

lso cut various other materials such as plastic & w

ead saw various & power various

th finish is

e used .

orce to

or cutting

wood.

MANUFA

When attache

tension.

The frames m

sizes. Blades are av

a standard hand hack

The pitch of t

hand blade & for lar

As hack-saw

As the blades

taken to prevent frac

Blades are ma

But for severa

their teeth, giving gr

On hack-saw

or away from the han

Resulting and

In normal use

bench, vice, the saw

Die:


hed to a C-shaped frame which holds a blade unde

may be adjustable to accommodate blades of diff

available in standardized lengths, usually 1011

or 1

ck-saw.

f the teeth can be anywhere from 14 to 32 per inch

arge power hack saw blade there are 3 tpi

w teeth are so small, they are set in a wave set.

es are normally quite brittle, so proper care should

acture of the blade.

made of carbon steel or low alloy steel.

eral decades now, hack-saw blades have used HSS

great improved cutting & tooth life.

w the blade can be mounted with the teeth facing

handle

nd cutting action on either pushes or pull stroke.

se, cutting vertically downwards with work held i

w blade Should be set to be face forward.

der

ifferent

r 1211

for

ch for a

uld be

SS for

g toward

in a


Die cutting is the posses of using die to shear weds of low strength

material such as rudder, tidier, cloth, plastic, sheet metal etc.

Die cutting can be done on either flat bed or by rotary process .

Rotary dry cutting is die cutting using a cylindrical die or a rotary

processes .

Dies are used to cut the external thread or the rod or pipe end.

Dies are made of high carbon steel or HSS .

The process of cutting external thread by dies is called dieing .

Sharing is also known as die cutting, is a process which cuts stock

without formation of chips or the off during or melting.

The die cutting action can be controlled by electric, hydraulic,

pressurized or manual surfaces.

Reamer:

� It is a multiple edge cutting tools.

� The process of enlarging the hole is called reaming.

� There are many different types reamer and there may

be designed for used as a hand tool or in a M/C tool such as milling

M/C or drill press.

� A typical reamer consists of a set of parallel straight or

helical cutting edge along the length of a cylindrical body

� Each cutting edge is grounded at a slight angle and with

slight undercut below the cutting edge

� This may be used to remove small amount of material.

� Reamers are made of high Carbon or Plain Carbon

Steel

Reamers ar of two types

� Hard Reamers

� Machine Reamers

MANUFA

Machining Process

Factors affect

The life of a

feed, depth of cut, c

and rigidity of the m

Cutting Speed:

The cutting

between the tool an

cutting edge of the to

It may be de

material. It is expres

Feed:

It is defined

cutting tool, relative

cutting speed directi


ss Parameters:

ecting tool life:

a tool is affected by many factors such as: cutti

t, chip thickness tool geometry, material of cutti

machine

g speed can be defined as the relative surfa

and the job or the amount of length that will

tool per unit of time.

defined as the speed which the cutting edge pass

essed in meters per min (mpm).

ed as the relation by small movement per cycl

ve to the workpiece in a direction which is usua

ction.

tting speed,

tting fluid,

rface speed

ll pass the

ass over the

cle of the

ually to the


Or

It is he distances the tools advances into or along the work piece. Each

time the tool point passes a certain position in its travel over the surface. It is

expressed as mm\tooth.

Depth of cut:

The depth of cut is the thickness of the layer of metal removed in one

cut or pass, measured in a direction perpendicular to the machined surface.

It is the vertical distance the tool advances into the work piece during

one revolution of job it is expressed in mm.

Selection of cutting speed, feed & depth of cut:

� Hard and strong materials require a lower cutting speed, soft & ductile

materials require higher cutting speeds.

� For light finishing cut – fine feed & higher speed roughing cut – low

feed & lower cutting speed.

� Large depth of cut – roughing operation

� Small depth of cut – finishing operation

� Cemented carbide, ceramics, satellite &

� Hss – high cutting speed tool

� Alloy or carbon steel tools – lower cutting speed.

Coolants & lubricants:

Cutting fixed sometimes referred to at lubricants or coolants are

liquids and gases applied to the tool and work piece to assist in the cutting

operations.


Purpose of cutting fixed:

� To cool the tool

� To cool the work piece

� To lubricate and reduce friction

� To improve surface finish

� To protect the finished surface from corrosion

� To cause chips break up into small parts

� To wash the chips away from the tool

Properties of cutting fluids:

1. High heat absorption for readily absorbing heat developed.

2. Good lubricating qualities to produce low-coefficient of friction.

3. High flash point so as to eliminate the hazard of fire

4. Stability so as not to oxide in the air

5. Neutral so as not to react chemically

6. Colorless so as not to produce any bad smell even when heated.

7. Harmless to the bearings.

8. Harmless to the skin of the operators

9. Non-corrosive to the work or the machine

10. Transparency so that the cutting action of the tool may be observed.

11. Low viscosity to permit flow of the liquid

12. Low priced to minimize production cost.


Choice of cutting fluids:

1. Type of operation

2. The rate of metal removal

3. Material of the work piece

4. Material of the tool

5. Surface finish requirements

6. Cost of cutting fluid.

Type of cutting fluids:

Water:

Pure water is the best cutting fluid available because of its highest

heat carrying capacity. But water corrodes the material very quickly so

water containing alkali, salt or water-soluble additive but little or no oil or

soap are some times used as coolant.

Soluble oils:

These are emulsions composed of around 80% or more water, soap

& mineral oil. The soap acts as an emulsifying agent which breaks the oil

into minute particles to dispose them throughout the water. The water

increase the cooling effect and the oil provide the lubricating properties.

Straight oils:

The straight oils may be

a) Straight mineral oils, kerosene, low-viscosity petroleum fraction

such as mineral seal, or higher viscosity mineral oils

b) Straight fixed or fatty oils consisting animal, vegetable or synthetic

equivalent, lard oil etc.

c) They have both cooling and lubricating properties


Mixed oils:

This is a co0mbination of strength mineral and strength fatty oil.

This makes oil excellent lubricant and coolant for anosmatic screw-machine

work.

Chemical additive oil: straight oil or mixed oil when mixed- up with

sulphur or chorine is known as chemical additive oil. Sulphur and chloral

are used to increase both lubricating and cooling qualities. These oils used

for machining tough, stivgy7 low carbon steels.

Chemical compounds: these compounds consists mainly of a rust

inhibitor, such as sodium nitrate, mixed with a high percentage of water.

Solid lubricants: stick waxes. And bar soaps are sometimes used as

lubricants.

Metal cutting and cutting tools : in the metal working industry the

various working processes fall into groups.

Not-cutting shaping – forgery, pressing, drawing

Cutting shaping – turning, drilling, milling.

Cutting tools

A cutting tool may be used either for cutting a part or for removing

chips.

Cutting tools are mainly divided into two groups.

� Single point cutting tool

� Multipoint cutting tool

A single point cutting tool consists of a sharpened cutting part

called its point.

Ex: lathes, slotting machines

Multipoint cutting tools have arrangement of two or more single

point tools as a unit.

Ex – milling cutting, broaching tool,twist drill.

MANUFA

Cutting tool nomen

It means sche

cutting tool.

Shank:

It is the main

Flank:

The surface o

called flank of the to

Heel:

It is the inter

Nose:

It is the point

intersection.


enclature:

hematic naming of the various parts and angles of

in body of the tool.

or surfaces below and adjacent to the cutting edg

tool.

tersection of the flank and the base of the tool.

nt where the side cutting edge and end cutting edg

of a

dge is

dge


Cutting edge :

It is the edge on the face of the tool which removes the metarial from

the work piece. The total cutting edge consists edge (major), end cutting

edge (minor) and the nose.

Face:

The surface against which the chip slides upward.

Base:

Tt is the undersice of the shank.

Rake:

It is the slope of the tap away from the cutting edge. Larger the rake

angle, the cutting force and power reduce.

Designation of cutting tools: there are two system to designate the tool

shape

1. American standards association system (ASA)

Or

American national standards institute (ANSI)

2. Orthogonal rake system. (ORS)

The various tool angles are:

1. Side cutting edge angle (Cs): (Lead angle)

The angle between the side cutting edge and side of the tool

shank

2. End cutting edge angle (Ce):

This is the angle between the end cutting edge and a line normal to

the tool shank


Side relief angle:

It is the angle between the portion of the side flank immediately below

the side cutting edge and a line perpendicular top the base of the tool

measured at right angle to the side flank.

End relief angle

It is the angle between the portion of the end flank immediately below

the side cutting edge and a line perpendicular to the base of the tool measured

at right angle to the end flank.

Back rake angle:

It is the angle between the face of the tool and s line parallel to the

base of the tool and measured in a plane perpendicular to the side of the

cutting edge. The angle is +ve – If side cutting edge slopes downwards from

the point towards the shank.

-ve – if the slope of the side cutting edge is reverse.

Side rake angle :

It is the angle between the tool face and a line parallel to the base of

the tool and measured in a planer perpendicular to the base and side cutting

edge. This angle gives slope of the face of the top from the cutting edge.

The angle is – ve – if the slope is towards the cutting edge

+ve - If the slope is away from the cutting edge

Purpose of tool angles

Cs – It is the angle which prevents interface as the tool enters the

work material. This angle affects tool life and surface finish 150 top 300 is

kept for general machining.

Ce – It provides a clearance or relief to the trailing end of the cutting

edge to prevent rubbing or drag between the mechanical surface and the non

cutting part of the cutting edge 8 to 150 is satisfactory.


These angles are provided so that the flank of the tool clears the

workpiece surface and there is no rubbing between them 5 to 150 is given.

Larger the rake angle smaller the cutting angle and lower the cutting

force and power

The rake angle is small for cutting har4d materials and large for

cutting soft ductile materials. It may be – ve or zero.

A flat cold chisel is a single point tool used at the branch and the

point is considered as wedge.

For mild steel a rake angle of 300 and wedge angle of 600 are

recommended

Using a cold chisel with no clearance angle, the loss through friction

is small as are cutting point is in contact with the metal

The force hammer below F is transmitted at approximately 900 to the

cutting face ac and these sets up shear stress across the shear plane ab.

If the hammer blow is heavy as , the metal will shear across the shear plane

and move up to the face ac as continuous chip.

The energy required to shear the metal will be the shearing force

along the shear plane and this force is proportional to the length of the shear

force is propotional to the length of the shear plane and the greater the energy

required to the shear of metal

A hack saw blade is a multi-point tool and has a very large number of

wedges like points each with its own rake and clearance angle.

The rake is necessary but too much rake makes the tooth weak

A large amount of energy would be lost in overcoming the frictional

forces set up if there is clearance.

The hollow space between each tool is sloped more sharply to give

the form if this would be too

Shallow it would be closed with chips of the metal being cut


Taps are used for cutting internal threads on work materials. it

consists of a no of teeth arranged uniformly across the whole die body when

it rotates in a particular direction i.e clockwise or anticlockwise .

The rake angle is provided to reduce the shear forces during cutting &

less torque will be required to shear the metal. There is no provision for

clearance angle in the die.

It is a multi point cutting tool used for enlarging or finishing a

previously drilled or bore hole to give a good finish and accurate dimension.

It removes very small amount of material from the work piece.


Page 25

Lathe Machine

Chapter-3


Page 26

Lathe machine:

The lathe machine is the one of the oldest machine tools and came the

early tree lathe which was a device for rotating and machining a piece of

lathe between two adjacent trees. a rope would round the work with its one

end attached to a flexible branch of trees and end is pulled by a man to rotate

the job hard tools are used them.

Function of lathe machine:

The main function of lathe machine is to remove metal from a piece

of work to give it the required shape and size. The work is held securely and

rigidly on the machine and then turn against the cutting tools which is

remove metal from the work in the forms of chips.

Types of lathe:

� speed lathe:

o Wood working

o Centering

o Polishing

o Spinning

� Engine lathe:

o belt drive

o Individual motor drive

o Gear head lathe

� Bench lathe:

� Tool room lathe

� Caps & turret lathe

� Special purpose:

o Wheel lathe

o Gap bed lathe

o Turret lathe

o Duplicating lathe

� Automatic lathe:


Page 27

The speed lathe:

� It is the simplest of all types of lathe.

� It consists of a bed, headstock, a tailstock and a too post mounted on

an adjusted slide.

� There is a no feed box, lead screw or conventional type carriage.

� The tool is mounted on the adjustable slide and is fed into work purely

by hard control.

� Spindle speed is very high.(range from 1200 to 3600 rpm).

� This is used for word working, spinning, centering, polishing.

The engine lathe or centre lathe:

� The engine lathe in the early ware driven by steam engines

� It consists of bed, head stork, and tail stork.

� More robust head stock and contains mechanism for driving the

spindle at multiple speeds.

� Belt driving lathe – receives power from an overhead live shaft

� Individual motor drive- receiving power from an individual motor

� Gear head lathe –gets power from a constant speed motor.

The bench lathe:

� The small lathe mounted on a bench

� It consists of all the parts but small in size.

� It is used for small & precision work.

The tool room lathe:

� It is similar to engine lathe.

� It has spindle speeds ranging from very low to high up to 2500 rpm.

� It consists of chuck, taper turning attachment, thread charging dial,

steady rest, coolant etc.

� This is used for precision work on tools, dies, gases & for accuracy

works


Page 28

Capstan and turret lathe:

� This is the development over engine lathe.

� The tail stock is replaced by a hexagonal turret, on the face of which

multiple tools are fitted

� Several operations can be done on a work piece without resetting of

work or tools & a no. of identical parts can be produced in minimum

time.

Special propose lathe:

� They are used for special proposes.

� The Wheel lathe – for finishing journals &turning the thread on rail

road car and locomotive wheels gap bed lathe- to swing extra large

diameter pieces.

� T-lathe – for machining of motor for jet engines the axis of the lathe

bed is right angles to the axis of the head store spade.

� Duplicating lathe used for duplicating the shape of a flat or round

template on the work piece

Automatic lathe:

� These are high speed, heavy duty, mass production lathes with

complete automatic control.

� After the tools are set and the machine is started is performs

automatically all the operations to finish the job.

� The changing of tools, speed s and feeds are done automatically.

� After the job is complete, the machine will continue to repeat the

cycles producing identical parts.


Page 29

Specification of lathe :

� The height of the centres from the bed.

� The swing diametre over bed. This is the largest diameter of work

that will revolve without touching the bed and is twice the height of

the centre measured from the bed of the lathe.

� The length between the centers. This is the max height of work that

can be mounted between the lathe centres.

� The swing dia over carriage. This is the biggest dia of work that can

be less than the swing dia over bed. This is the maximum bar stock

will pass through hole of the headstock spindle .

� The length of the bed: This indicates the approx. floor space occupied

by the lathe

The work piece is held in a chuck or between centers and rotated its

axis at uniform speed .the within tool held in the tool post is fed in to the

work spices for a desired depth. the tool may be given linear motion in may

direction salve there is a relative motion between the work piece and tool ,

the material is removed the form of chips & desired shape is obtained .

MANUF

Different parts of a

1. Bed

2. Head stock

3. Tail stock

4. Carriage

5. Feed mechan

6. Screw cuttin

BED:

The be

iron. It is a

deflection an

carriage. On

ways. The ou

The guide wa

900


f a lathe :

anism

ing mechanism

bed is the base or foundation of the lathe. It is ma

a massive and rigid casting made in one piece

and vibrations. It supports the head stock, tail

n the top of the bed, there are two sets of slides

outer ways for carriage and inner ways for the t

ways may be flat and inverted –v having included

Page 30

ade of cast

ce to resist

il stock and

es or guide

e tail stock.

ed angle of

MANUF

Head stock:

The head stoc

of the lathe. It

multiple speeds.

The spindle o

It protrudes from

holding derives

nose is turned so

rotate the work p

live centre.


tock assembly is permanently fastened to the left

It provides mechanical means of rotating the

e of head stock is made of carbon or nickel chro

rom gear box and contains means for fast end

s like chuck, face plate, dog plats, live centred

so that face plate or chuck can be mounted on it

piece. Hollow spindle is tapered at the nose to re

Page 31

ft hand end

e work at

hrome steel.

nding work

ed spindle

it hold and

receive the

MANUF

Spindle is ho

which long bar s

max’m size of ba

Power is supp


hollow throughout its length throughout its lengt

r stock can be fed. The size of spindle hole deter

bar stock that can be machined

pplied from an electric motor or V-belt.

Page 32

gth through

ermines the

MANUF

Tail stock or loo

The tail stock

the bed and it is a

any position to ac

It has two use

1. Supports the

centres.

2. To hold a too

tapping etc.

CARRIAGE:

In between th

on the bed ways

to it either longit


loose head stock:

ck is located at on the inner ways at the right ha

is a non-rotating part which slides and can be clam

accommodate different lengths of work pieces.

ses:

e other end of the work when it is machined betw

ool for per forming operations such as drilling, rea

the head stock and tail stock is the carriage. It is

ys and its purpose is to hold the cutting tool and

itudinal or cross feed. It consists of the following

Page 33

hand end of

amped to it.

tween two

reaming,

is movable

d to impart

ng parts:

MANUF

1. Saddle:

It is an

bed. It carries

2. Cross slide:

It is m

is to the cent

mixed by me

wheel or by p


an H-shaped cashing that fits over the outer wa

ies the corss-slide and tool post.

mounted on saddle. It provides cutting tool moti

ntre like of the lathe. This is known as cross sli

means of feed screw, which is controlled by a sm

power feed.

Page 34

ways of the

otion which

slide can be

small hand

MANUF

3. Compound r

It is m

post. It has a

axis. It can b

means of a s

graduated dia

4. Tool post:

It is m

The tool pos

clamped in a

desired angle

way


rest:

mounted on the top of the cross slide. It support

s a graduated base and can be swiveled around

be swivelled around a vertical axis. It can be m

a screw which is controlled by a small hand w

ia & not by power feed.

mounted on the top of the compound rest to hold

ost can be moved on the compound rest and

any position. It can be rotate also to hold the

le.1. single tool post 2. Four bolt 3. Open side

Page 35

orts the tool

d a vertical

e moved by

wheel and

old the tool.

and can be

he cutter in

de 4. Four

MANUF


Page 36

MANUF

5. Apron:

lathe is calle

operating the

contains frict

which is close

FEED MECHA

Feed is the di

revolution of he

cross and angula

Longitudinal fee

When the to

termed as longit

and is effected by

Cross feed:

When the to

termed as cross

movement of cro


The portion of the carriage which extends in

lled apron. It contains the gears, clutches. And l

the carriage by hand or power feeds. The ap

iction clutches for automatic feed of a split nut o

osed over for cutting screw threads.

ANISM:

distance the tool advances into the work piece thr

head stock spindle a lathe tool has 3 types- lon

lar.

feed:

tool moves parallel to the lathe axis, the mov

gitudinal feed. It is used in cylindrical turning o

by movement of carriage.

tool moves parallel to the lathe axis, the mov

ss feed. It is used in facing operation & aff

ross slide.

Page 37

in front of

d levers for

apron also

t or half nut

through one

ongitudinal,

ovement is

operations

ovement is

affected by


Page 38

Angular feed:

When the tool moves at an angle to the lathe axis, it is termed as

angular feed. It is used in taper turning and affected by movement of

compound rest.

Angular feed is hand operated where cross feed & longitudinal feed

can be both hand & power operated.

Third cutting mechanism:

The rotation of the head screw is used to transverse the tool along

were to produce screw thread. The half nut mechanism makes the carriage to

engage or disengage or disengage with the lead screw. The two halves of the

nut are connected in the cam slots in a circular disc by two pins. When the

disc is rotated by a hand lever attached to it, the pins being guided in the cam

slots serve to open or close the split nuts and thus engages or disengages with

the lead screw.

The half nuts slide within the guide or frame. Closing the half nuts

causes the carriage to move a fixed distance for each revolution of the

spindle. The direction in which it moves depends upon the position of the

feed reverse lever on the head stock. The split nut is used only for thread

cutting and never for any other operation.

Lathe operation:

Lathe operations are performed by following methods.

Operations which are performed in a lathe either by holding the work

piece between centers or by a chuck:

1. Straight turning

2. Shoulder turning

3. Chamfering

4. Thread cutting

5. Facing

6. Knurling

7. Filling

8. Taper turning


Page 39

9. Eccentric turning

10. Polishing

11. Grooving

12. Spinning

13. Spring winding

14. Forming

Operations which are performed by holding the work by a chuck or a

face plate :

1. Drilling

2. Reaming

3. Boring

4. Counter boring

5. Taper boring

6. Internal thread cutting

7. Tapping

8. Under cutting

9. Parting off

Operations which are performed by using special attachments:

1. Grinding

2. Milling

Facing:

Facing is the operation of for generation flat surface perpendicular to

the rotational axis of spindle. The tool is fed to the axis of rotation of the

work piece. A properly ground facing tool is used. A regular turning tool

may also be used. a spindle speed is selected and the lathe is started. The tool

is brought in to clean stock from the centre and fed out word by hand. Feed is

given by cross slide.

Turning:


Page 40

Turning in lathe is to remove excess material from the work piece to

produce a cone-shaped or a cylindrical surface.

Straight turning:

The work is turned straight when it is made to rotate about the lathe axis,

and the tool is fed parallel to the lathe axis. It produces a cylindrical surface

by removing excess metal from the work piece.

After facing the ends and drilling the centre, the job is

carefully mounted between the centres using a lathe dog attached to the

work piece, the bent tail of the dog fitting into the slot provided on the

catihplat. A properly ground a right hand turning tool selected. The

machine is started after the work piece and tool is properly set and correct

spindle speed is determined.

The automatic feed is engaged to move the carriage to the

desired length, then the feed is dis engaged and the carriage is brought

back to the starting position. The process is repeated until the job is

finally finished after two or three similar cuts.

There are two kinds of cuts in a machine shop work.

1. Roughing cut or rough turning.

2. Finishing cut or finish turning.

Rough turning:

It is the process of removal of excess material from the work piece in

a machine time by applying high rate of feed and heavy depth of cut. The

doc is from 2 to 5 mm & feed rate is 0.3 to 1.5 mm per over.

Finish turning:

It requires high cutting speed, small feed and a very small depth of

cut to generate a smooth surface. The doc is from 0.5 to 1 mm & feed 0.1 to

mm per rev.

Shoulder turning:

When a work piece having different diameters is turned, the surface

forming the step from one diameter to other is called shoulder turning


Page 41

The principle of thread cutting is to produce a helical groove on a

cylindrical or conical surface by feeding the tool longitudinal when the job

is revolved between centres or by a chuck. The longitudinal feed should be

equal to the pitch of the thread to be cut per revolution of the work piece.

The lead screw of lathe, through which saddle receives its traversing

motion, has a definite pitch. A definite ratio between the longitudinal feed

and rotation of the headstock spindle should therefore be found out. So that

the relative speeds of rotation of the work and the lead screw will result in

the cutting of a screw of the desired pitch.

This is affected by change gears arranged between the spindle and

the lead screw or by the change gear mechanism or feed box used in a

modern lathe where it provides a wider range of feed and the speed ratio

can be easily and quickly changed

Taper Turning:

A taper may be defined as a uniform increase or decrease in diameter

of a piece of work mannered along its length.

In lathe taper turning means to produce a conical surface

by gradual reduction in dia from a cylindrical work piece. The amount of

taper is specified by the ratio of the difference in dia of taper to its length let

it be denoted by k and termed as concity,

K = D-d/l

There are different methods for taper turning in lathe:

1. By a broad nose tool.

2. By setting over the tail stock centre.

3. By swivelling the compound rest

4. By a taper turning attachment.

5. By combining longitudinal feed & cross feed in a special lathe.

MANUF

Taper turning in a

Abroad nose

half taper angle, an

surface. The half an

The work is held in a

It is used to tu

Taper turning by se


a form tool:

se tool having straight cutting edge is set on to th

and is feed straight into the work to generate

angle of taper will correspond to (90-SCEA) of

a chuck or clamped on a face plate.

turn short length of taper only.

setting over the tailstock:

Page 42

the work at

e a tapered

of the tool.

MANUF

The axis of r

lathe axis and the to

the axis of rotation

taper.

This is done b

from the operation b

This is used f

By swivelling the co

In this metho

axis and feeding the

The tool mou

base, graduated in

desired angle the co

lathe axis to turn a st


rotation of the work piece is shifted at an ang

tool is fed parallel to the lathe axis. The angle

n of the work piece is shifted is equal to half an

by the tail stock is made to slide on its base or aw

by a set over screw.

d for turning small taper (not exeed 80) on long jo

compound rest:

hod the taper is formed by rotating the work piec

e tool at an angle to the axis of rotation of work p

ounted on the compound rest is attached to a

n degree, which may be swivelled and clampe

compound rest car be swivelled at 45 on either s

steep taper. The angle is determined by

Page 43

ngle to the

le at which

angle of the

away

jobs.

ece on lathe

piece.

a circular

ped at any

r side of the


Page 44

KNURLING:

Knurling is the process of embossing a diamond shaped pattern on

the surface of a work piece. The purpose of knurling is to provided an

effective gripping surface or a work piece to prevent it from slipping when

operated by hand.

The operation is perturbed by a special knurling tool which

consists of 1 set of steel rollers in a holder. The tool is pressed against the

revolving workpiece producing depressions in a regular pattern. On the

surface of the work piece it is done at the speed ¼ th of that of turning and

planty of oil is flowed on the tool and work piece feed varies from 1to 2mm

per rev.


Page 45

Parting off:

Parting off is the operation of cutting a work piece after it has been

machined to the desired size & shape the job rotated on a chuck or face

plate at half the speed that of turning and a narrow parting of tool is feed to

the lathe axis by. Hand feed. The feed varies from 0.07 to 0.15 mm per rev.

And depth at let ranges from 3 to 10 mm .

Internal machining:

Drilling:

Drilling is the operation of production a cylindrical hole in a work

piece by rotating cutting edge of a cutter known as drill .

The work piece is revolved in a chuck or faceplate and the drill is

held in the tailstock drill holder or in a drill chuck. Feeding is effected by

the movement of the tail stock spindle (adopted for regular shaped work

pieces)

The drill is held and driven by a drill chuck attached to the headstock

spindle and the work is held against a pad supported by the tailstock

spindle. Feeding is effected by the movement of the tailstock spindle

(adopted for irregular shaped work pieces


Page 46

Boring:

It is the operation of enlarging and truing a hole produced by

drilling, punching, casting co-forging the

The work is revoluted in a chuck or a face plate and the tool which is

flitted to the tool post is fed in to the work . One piece forged tool is used for

boring small hole , whereas a boring bar with a tool bit attached to it is

suitable for machining a large hole the doc is giver by the cross slide screw

and the fade is feeder by the longitudinal travel of the carriage .

The work is clamped on the carriage and a boring bar holding the

tool is supported between the centres made to revolute. Longitudinal

movement of the carriage provides feeding movement and the doc is given

by adjusting the position of the tool insert.

Internal thread to external forced cutting operation , the different

being in the carriage provides feeding movement and the doc is given

adjusting the position of the tool insert .

Internal thread cutting:

It is similar to external thread cutting operation , the different being

is the tool used . the tool is similar to boring tool with the cutting edges

ground to the shape conforming to the type of thread to be cut the hole is

first bored to the root dia of the thread for cutting metric to read the

compound slide is swivelled 30� to words the headstock . the tool is fixed on

the toolpost or on the boring bar after strive it at tught angle to the lathe axis


Page 47

, using a trove gauge the do is given by compound slide and the to read is

finished in the usual manner.

Safety measures during machining:

Some safety precautions should be needed while working on lathe.

� Before operating the machine, one should fully understand its

operations controls and how to stop it.

� All gears and gear ends of the lathe should be properly guarded.

� Safety goggles are preferred to avoid damage to eyes by flying

chips.

� Avoid wearing rings, bracelet or watch.

� Machine should not be left running and operator should be alert

during a job.

� Before starting a lathe spindle by power, spindle should be rotated

by one revolution by hand to make it sure that no fouling is there.

� Safe distance from revolving chuck should be maintained.

� Tools and instruments should not be placed over lathe bed.

� Sliding parts of the lathe should be cleaned and lubricated

periodically.

� Chips should never be removed by hand. It can be removed by

brush.

� Before starting the machine, the work should be clamped

properly.

� Before moving the carriage, the carriage clamping screw should

be unlocked.

� On hearing unusual noise, machine should be stopped

immediately and should not be operated till the fault is clear.


Page 48

Capstan & Turret lathes:

A capstan or a turret lathe is a production lathe used to

manufacture any number of identical pieces in the minimum time.

The main feature is the six sided block mounted on one end of the

bed replacing the normal tailstock six tools can be mounted at on

cross slide two tool posts are mounted, one in the font and the

other in the rear. Each one can hold four tools .Thus the total

carrying capacity is a maximum 14 tools

Difference between CAPSTAN &TURRET and an ENGINE LATHE

CAPSTAN &TURRET ENGINE LATHE

1. The head stock possesses

wider range of speeds and in

heavier in construction it

require 15 hp power to drive

the spindle.

1. It requires 3hp to drive the

spindle.

2. The tool post mounted or the

cross slide is a four way & a

rear tool post is mounted on

the rear side which also holds

4 tools.

2. In engine lathe one tool can

be mounted at one time for

different operation.

3. In turret lathe, the tail stock is

replaced by a turret which is a

hexagonal block which

contains 6 tools on each face.

3. It can accommodate one tool

of limited size.

4. The feed movement of each

tool set on square or

hexagonal turret is regularity

by stops & feed strips.

4. The feed movement is given

by hand.

5. Combination cuts can be

taken by mounted two or

more tools on the same face

of the turret.

5. Combination cuts cannot be

done.

6. The labour cost is less. 6. Labour cost is more.


Page 49

7. The threads are cut by

die heads & taps.

7. The threads are cut by lead

screws Centre lathe is

suitable for odd jobs having

different shapes & sizes.

8. Turret lathes are suitable for

producing large no. Of

identical pieces.

8. The threads are cut by lead

screws.

Difference between capstan & turret lathe:

Capstan lathe Turret lathe

1. Its turret head is mounted in

slide, which moves on the

guide ways produced on the

saddle.

2. For feeding the tool to the

work, the saddle is fixed at

convenient distance from the

work.

3. It is suitable for smaller size

& lighter jobs. It is not

suitable for heavy cutting

condition.

4. It is suitable to work for

smaller bar upto 60 mm dia.

5. The turret head may

hexagonal or circular.

6. It is smaller in size compound

to turret lathe.

7. The tool traverse is faster and

offer less fatigue to the hands

of the operator.

1. Its turret to head is mounted

directly on the saddle.

2. For feeding the tool to the

work, the entire saddle unit is

moved.

3. It is suitable for long and

heavy work and severe cutting

condition.\

4. It is used to work for large size

bar upto 200mm dia.

5. Turret head is hexagonal.

6. It is large in size as compared

to capstan lathe.

7. The tool feeding is relatively

slower and provide more

fatigue to operator hands.

MANUFA

The capstan or ram

The capstan

turret on ram or sho

ways. the feeding m

right and when the

and the toll mounte

machine is lighter in

diameter.


am type lathe:

n or ram type turrent or capstan lathe carries a h

hort slide,the ram slide longitudinally on a sadd

movement is obtained when the ram moves fro

e ram moved backward the turret indexes auto

ted on the next face comes into operation. Thi

in construction and is suitable for machinery ba

Page 50

a hexagonal

ddle on bed

from left to

utomatically

his type of

bar of small

MANUFA

The turret or saddl

The hexagona

unit moves back and

accommodate longer

construction and for

Multiple Tool holde

Both capstan

capstan head in cap

capstan head usually

axis vertical or at an

octagonal in shape h

commonly used. It i

vertical turret where


dle type lathe

nal turret is mounted directly on the saddle and

nd forth on the bed ways to apply feed. The ma

ger work pieces than that in a capstan lathe. It is

or larger bar work and chucking work.

lder.

an and turret lathe carry a multiple holding dev

apstan lathe and turret head in case of turret l

lly circular carrying six slots. It can be mounted

an inclination. The turret head can be square, hex

having one hole on each face. The hexagonal typ

t is always mounted with its axis vertical except

re the axis of rotation of the turret head is horizon

Page 51

d the whole

achine can

is heavier in

evice called

t lathe. The

ed either its

exagonal or

ype is more

t in case of

ontal.T

MANUFA

Parts of capstan an

Bed:

The bed is lo

on which the carria

strength, rigidity and


and turret lathe:

longer box like casing provided with accurate gu

iage and turret slid are mounted. It is designed

nd permanency of alignment under heavy duty ser

Page 52

guide ways

d to ensure

services.


Page 53

Headstock:

It is similar to engine lathe in construction. It is larger & heavier in

construction and wider range of speeds speed may rang form 30 to 2000rpm

two types of headstocks.

a) Electric head - variable speed motor is mounted.

b) All geared heads - wider range of speeds

The spindle is hollow and bar stock can be fed thorough a collar chuck .

Gross slide & saddle:

There are two types of slides used in turret lathe

� Conventional type

� Slide hunk type

The conventional type of Carriage Bridge the gap between the front

and rear bed wage

The slide hunk type carriage is generally fitted with heavy duty turret

lathe. Large diameter of work pieces can be swing over bed. The

longitudinal movement of each tool may be regulated by using stop bars or

shafts set against the stop fitted on the bed and carriage. The stops are set so

the each tool will feed into the work to desired length the stop bars are

indexed by hand

The turret saddle and auxiliary slide :-

The turret saddle bridges the gap between two bed ways. The

hexagonal turret is mounted o9n the auxiliary slide. In turret lathe, the turret

is directly mounted on the top of the saddle.

The turret is a hexagonal shaped tool harder intended for six or more

tools. The centre line of each hole is coincides with the axis of the lathe. Six

stop bars are mounted on the saddle which restricts the movement of each

tool mounted on each face of turret to be fed predetermined amount. After

one operation the turret is brought backward from the spindle nose the turret

indexes automatically.

MANUFA

Capstan and turret

Turret head indexi

This is an inv

the spindle. The in

keyed to the spindle

the saddle locks the

movement of the tur

A pin is fitt

actuating cam and th

positions. Both the

reaches the backwar

groove in the index

of the cam and thus u

The spring lo

ratchet plate, causes


ret lathe mechanism:-

xing mechanism:-

inverted plan of turret assembly. The turret is mo

index plate, the, bevel gear and an indexing ra

le. The plunger fitted within the housing and mo

he index plate by spring pressure and prevents a

urret as the tool feeds into the work.

fitted on the plunger projects out of the hous

the indexing pawl are attached to the lathe bed

he cam and the pawl are spring loaded. As t

ard position, the attaching cam lifts the plunger o

x plate due to the riding of the pin on the bevelle

s unlocks the index plate.

loaded pawl which by this time engages with a

es the ratchet to rotate as the turret head moves ba

Page 54

mounted on

ratchet are

mounted on

s any rotary

using. An

d at desired

the turret

r out of the

lled surface

a groove of

backward.


Page 55

When the index plate or turret rotates through one sixth of revolution, the pin

and the plunger drops out of the cam and the plunger locks the index plate at

the next groove.

The turret is thus indexed by one sixth of revolutions and again

backed into the next position automatically. The turret holds the next tool is

now fed forward and the pawl is released from the ratchet plate by the

spring pressure.

The bevel opinion meshes with the bevel gear mounted on the turret

spindle. The extension of the pinion shaft carries a plate holding six

adjustable stop rods. As the turret rotates through one sixth of the revolution

, the bevel gear causes the plate to rotate.

The ratio of the teeth between the pinion and the gear are so chosen

that when the tool mounted on the face of the turret is indexed to bring it to

the cutting position, the particular stop rod for controlling the longitudinal

travelling of the tool is aligned with the stop.

The setting of the stop rods for limiting the feed of each operation

may be adjusted by unscrewing the lock nuts and rotating the stop rods on

the plate. Thus, six stop rods may be adjusted for controlling the

longitudinal travel of tools mounted on six faces of the turret.

Bar feeding mechanism:-

On the capstan and turret lathes, some arrangements is need to be feed

the bar stock through the collet or chuck after each finished work piece is

parted off. Bar may be fed by hand also but has a safety measure one has to

stop the machines first for every feeding of bar. It also wastes lot of time.

MANUFA

In this metho

collect without stopp

A bar feeding

of lathe. Bar is fed

stock passes through

connected with a sle

Under the act

At the end of the par

length of the bar. A

control lever, the ba

and strike with the b

The bar stop

the required bar len

operated to close the


hod the bar is push forward as soon as it release

pping the lathe.

ng mechanism is fitted with a capstan lathe is the

d against the rotating sleeve and the collet chuck

gh the spindle of the collet chuck. One end of th

leeve and the other end is attached with a weight.

action of the weight, the bar moves towards the he

arting off operation on the job. It is needed to fee

. As soon as the collet is opened by operating

bar is release and is automatically rushes out of

bar stop.

p mounted on the capstan head for the purpose

ength projecting out of the colet. The colet leve

he collet and hold the bar tightly.

Page 56

se from the

he back side

ck. The bar

the rope is

ht.

head stock.

eed the new

g the Colet

of the collet

e of getting

ver is again


Page 57

Tooling layout:

The tool layout for a job constitute the predetermined plan for the

order and method of machining operation necessary to produce it. For

preparation of the layout, it is necessary to have a finished drawing of the

part to be produce. The tool layout consists of two steps: preparation of

operation sheet.

Sketching the plan showing various tolls fitted into the turrent faces

and the cross slides, in proper sequence.

Production of hexagonal bolts:-

Operation no. description

operation

of tool position tools

1 Hold in collet 1st

position

turret Bar stop

2 Turn to 16 mm

dia

2nd

position

turret Roller steady bar

turning tool

3 Form end of the

bolt

3rd

position

turret Roller steady bar

ending tool

4 Screw 16 mm 4th

position

turret Self opening die

head with chasers

for 16 mm

5 Chamfer Front cross slide

tool past

Chamfering tool

6 Parting off Rear tool post Parting off tool

For bush:-

Sl no Sequence

operation

of Machine shop Tools / gauges

1 Fixed end

deep

2mm Turret

position1

(rear slide)

lathe Bar ending tool

2 Feed out bar stop Position 2 Bar stop

3 Stop for drilling Position 3 Centre drill

4 Drill hole 10 mm Position 4 Drill 10 mm dia,


Page 58

dia, and rough turn

16.5dia×36 mm

rough

tool

turning

5 Finish turn to 16.10

mm dia, bore 11.5

dia × 36 mm and

chamfer 0.3×45°

Position 5 Finish turn tool,

chamfering tool

and boring tool

³ Rough ream 11.8

mm dia×36 mm

Position 6 Reaming

rough

toll

7 Finish

11.8mm

mm

ream

dia × 36

Position 7 Reaming

finish

tool

8 Cut off to 31 mm

length

Position 8 Parting off tool

9 Chamfer other end

0.3×45°

Upright drill Chamfering tool

10 Drill oil hole Upright drill Drill 2mm

11 Cut oil grooves Special machine Groove cutter

12 Grind to 16 mm dia Cylindrical

grinder

Finish

wheel

grading

13 inspect Inspection

department

Limit gauges

1. Feed the bar stock to stop

2. Turn 14 mm dia with box tool

3. Turn 14.28 mm dia with box tool

4. Round end with roller steady ending tool

5. Centre with centre drill

6. Cut threads with die head

7. Form 17 mm dia and chamfer with tool from front square slide

8. Part off with cut of tool in rear tool


Page 59

Shaper

Chapter-4

Shaper:-

The shaper is a reciprocating type of machine tool intended to produce

flat surfaces. The surface nay be horizontal, vertical or inclined

Working principle:-

The job is fixed rigidly in a suitable vice or directly clamped on the

machine table. The tool is held in the tool post mounted on the ram of the

machine. This ram reciprocates to and fro , and in doing so , makes the tool

to cut the material in the forward stroke. No cutting takes place during the

return stroke of the ram. It is called idle stroke. The job is given an intended

feed, in a direction normal to the line of action of the cutting tool.


Page 60

Types of shapers:-

1. According to the type of mechanism used for giving reciprocating

motion to the ram.

a. Crank type

b. Geared type

c. Hydraulic type

2. According to the position and travel of ram .

a. Horizontal type

b. Vertical type

c. Travelling head type

3. According to the type of design of the table

a. Standard shaper

b. Universal shaper

4. According to the type of cutting stroke

a. Push type

b. Draw type

Specification of shaper:-

1. Maximum length of stroke(175-900mm)

2. Maximum horizontal travel of table

3. Maximum vertical travel of table

4. Maximum distance from table to ram

5. Tool box, vertical adjustment

6. Length and width of the table

7. Numbers and range speeds available

8. Numbers and range feeds available

9. Horse power and speed of driving motor

10. Weight of the machine and floor space required


Page 61

Crank shaper:-

This a most common type of shaper. It uses a crank mechanism to

change circular motion of a large bull gear into reciprocating motion of the

ram

Geared type:-

The reciprocating motion is effected by means of rack and pinion

Hydraulic shaper:-

The reciprocating motion is obtained by hydraulic power.

Horizontal shaper:-

The ram reciprocates in a horizontal axis

Vertical axis:-

The ram reciprocates in a vertical axis

Travelling head shaper:-

The ram reciprocates and moves crosswise to give required feed

Standard or plain shaper:-

The table has two movements, vertical and horizontal to give the

feed

Universal shaper:-

In addition of the two movements, the table can be swivelled about

on axis parallel to the ram ways.

Push type:-

The most general type of shaper used in common practice . the metal

is removed when the ram moves away from the column

Draw type shaper :-

The metal is removed when the ram moves towards the column of

the machine, draws the work towards the machine. The tool set is reversed

direction to that of a standard shaper.

MANUFAC

DIFFERENT PAR

BASE:-

The base pro

equipments present a

it is made of cast iro

can be bolted to the f

Column(housing):-

The column

base. It houses the r

top of the column

movement of the ram


RTS OF A SHAPER:-

provides stability for the shaper as it supports

t as well as absorb the forces coming due to the

iron and have a necessary arrangements of bolts

e factory floor.

-

n of the shaper is a hollow casting and is mount

e ram driving mechanism. For the ram and tabl

n, necessary guide ways are provided for t

am and the front vertical face is for cross rail.

Page 62

ts all other

the cutting .

lts so that it

nted on the

ble, on the

the linear


Page 63

Cross rail:-

The cross rail is mounted on the front vertical guideways of the

column. It has two parallel guide ways on its top vertical plane that are

perpendicular to the ram axis. The table may be raised or lowered to

accommodate different sizes of job by rotating elevating screw.

Saddle:-

The saddle is mounted on the cross rail which holds the table . on its

top crosswise movement of the table is powered by rotating cross feed

screw.

Table:-

The work table of a shaper is fastened to the front of the column. The

table is provided T-slots for mounting the work pieces. The table can be

moved up and down and crosswise by cross rail and saddle. Jobs can be

held by vice.

Ram:-

The ram is a reciprocating member of the shaper. It is

semicylindrical in form and heavily ribbed inside to make more rigid. It

slides on the guideways of the column. A single point cutting tool is

fastened in the tool post.

Tool head:-

The single point cutting tool is held in the tool post. The tool head

holds the tool provides vertical and angular feed movement and allows the

tool to have an automatic relief during return stroke. The vertical side of the

tool head has a swivel base which is held on a circular seat on the room.

The swivel base is graduated in degrees so that the vertical slide may

be set perpendicular to the work surface at any desired angle. By rotating

the down feed screw handle, the vertical slide carrying the tool executes

down feed or angular feed movement while machining vertical or angular

surface.

The amount of feed or depth of cut may be adjusted by a micrometer

dial on the top of the down feed screw. Apron consisting of clapper box,


Page 64

clapper block and tool post is clamped upon the vertical slide by a screw.

By releasing the clamping screw , the apron may be swivelled upon the

apron swivel pin either towards left or towards right w.r.t the vertical slide.

This arrangements is necessary to provide relief to the tool while making

vertical or angular cuts.

The two vertical walls on the apron called clapper box houses the

clapper block which is connected to it by means of a hinge pin. The tool

post is mounted upon the clapper block.

On the forward cutting stroke the clapper block fits securely to the

clapper box to make a rigid tool support on the return stroke a slight

frictional drag of the tool on the work lifts the block out of the clapper box

a sufficient amount preventing the tool cutting edge from dragging and

consequent wear. The work surface is also prevented from any damage due

to dragging.

Shaper mechanism:-

The metal is removed in the forward cutting stroke, while the return

stroke no matal is removed during this period.

To reduce the total machining time it is necessary to reduce time taken

by the return stroke. The shaper mechanism should be so designed that it

can allow the ram holding the tool to move at comparatively slower speed

during the forward cutting stroke and during the return stroke the ram move

faster rate to reduce the idle return time. The mechanism is called quick

return mechanism.

1. Crank and slotted mechanism

2. Whitworth quick return mechanism

3. Hydraulic shaper mechanism

Crank and slotted link mechanism:-

The motion or power is transmitted to the bull gear through a pinion

which receives is motion from an individual motor or overhead line shaft

through speed control mechanism. Speed can be changed by shifting gears.

A radial slide is bolted to the centre of the bull gear , carries a sliding

block into which the crank pin is fitted . rotation of the bull gear causes the


Page 65

crank pin to rotate at a uniform speed. Sliding block which is invented on

the crank pin is fitted within the slotted link. The slotted link is pivoted at

its bottom end attached to the frame of the column. The upper end is forked

and connected to the ram block by a pin.

As bull gear rotates causes the crank pin to rotate, the sliding block

fastened to the crank pin will rotate on the crank pin circle, and at same

time will move up and down in the slot giving a rocking movement which

is communicated to the ram. The rotary motion of the bull gear converted to

reciprocating movement of the ram.

When the link is in the position PM.ram will be at the extreme

backward of its stroke.

When at PN – extreme forward position PM

&PN are tangent to the crank pin circle.

C1C2⇨ forward cutting stroke

C2 C1 ⇨ return stroke

MANUFAC

It is clear tha

The angular velocit

rotates at uniform sp

Generally varies 2:1

Whitworth quick r

A bull gear is

rotate. The crank pla

on the face of the bu

is mounted. Sliding

connecting rod conn


that the angle made by the forward stroke> retu

city is constant ⇨ rotated by speed metre and

speed.

:1 and practical 3:1

return mechanism:-

r is mounted on a large fixed pin a upon which it

plate is pivoted eccentrically upon the fixed pin

bull gear is the crank pin 2 on top of which slid

ng block fits into the slot provided on the crank

nnects the crank plate by a pin and the ram by a p

Page 66

turn stroke.

d the crank

it is free to

n at 5.fitted

liding block

nk plate. ,a

pin.

MANUFAC

When the bu

the sliding block wi

on a crank circle of

plate to rotate about

Pin fitted on

and the rotary mo

movement in the ram

axis of reciprocating

line A3.

When the pin cutting

When the pin cutting

CB = cutting stroke

BC = return stroke(f

As angular velocity o


bull gear will rotate at constant speed the crank

will rotate on a crank pin with the sliding block w

of radius A2 and the sliding block will cause

ut the point 5 with a variable angular velocity.

n the other end of the crank plate will rotate in

otion of the pin will be converted into reci

ram. Similar to crank and connecting rod mechan

ing of the ram passes through the pin and norma

ing stroke is at position C ⇨ extreme backward p

ing stroke is at position B ⇨ forward position

(backward to forward)

forward to backward)

y of the crank pin is uniform for the time taken i.e

Page 67

k pin with

k will rotate

e the crank

in a circle

eciprocating

anism. The

mal to the

position

i.e,

MANUFAC

Hydraulic shaper m

In a hydrauli

piston moving in a c

The machine

chamber, a cylinder

The oil under a high

pass through the val

pressure on the pis

perform forward stro

the ram.


r mechanism:-

ulic shaper the ram is moved forward and backw

cylinder placed under the ram.

ine consists of a constant discharge oil pump

er and a piston. The piston rod is bolted to the r

igh pressure is pumped from the reservoir and is

alve chamber to the right side of the oil cylinde

iston. This causes the ram connected to the p

troke ward by a piston moving in a cylinder plac

Page 68

kward by a

p, a value

ram body.

is made to

der exerting

piston to

laced under

MANUFAC

The machine

chamber , a cylinder

The oil under a high

pass through the val

pressure on the pisto

This causes

stroke, and any oil

reservoir through th

shaper dog hits agai

positions within the

the left side of the pi

Oil present o

reservoir. At the end

reversing lever alter

cycle is repeated.


ine consists of a constant discharge oil pump

der and a piston. The piston rod is bolted to the r

igh pressure is pumped from the reservoir and is

alve chamber to the right side of the oil cylinde

ton.

s the ram connected to the piston to perform

il present on the left side of cylinder is discharg

the throttle valve. At the extreme of forward s

gainst the reversing lever causing the valves to a

e valve chamber oil under high pressure is now

piston causing the ram to perform return stroke.

on the right side of the piston is now discharg

nd of the return stroke another shaper dog hits a

tering the direction of stroke of the piston and

Page 69

p, a value

e ram body.

is made to

der exerting

rm forward

arged to the

stroke, the

o alter their

w opened to

arged to the

against the

d thus the

MANUFAC

The quick re

volume of the cylin

presence of piston r

fixed period, the sam

side of the cylinder.

This will me

smaller stroke volu

increasing the speed

Automatic cross fee

In a shaper b

or bevel surfaces ar

head by hand. Cros

surface. This is done


eturn motion is effected due to the difference

linder at both ends, the left hand being smaller d

rod. As the pump is a constant discharge one,

same amount of oil will be pumped into right or

ean that the some amount of oil will be packed

lume causing the oil pressure to rise automati

ed during the return stroke.

feed mechanism:-

r both down feed and cross feed can be obtained

are produced by rotating the down feed screw o

ross feed movement is used to machine a flat h

ne by rotating the cross feed screw by hand or po

Page 70

ce in stroke

r due to the

e, within a

or left hand

ed within a

atically and

ed. Vertical

of the tool

t horizontal

power.


Page 71

Rotation of the cross feed screw causes the table to move sideways at

the end of each return stroke to bring the uncut surface of the work. This is

done by automatic cross feed mechanism of shaper.

The rotation of the bull gear causes the driving disc to rotate in a

particular direction. The driving disc is T- slotted and position of the crank

attached to the connecting rod may be altered to give different throw of

eccentricity. The other end of the connecting rod is attached to the rocking

arm by a pin. The rocking arm is fulcrum at the centre of the ratchet wheel.

The ratchet wheel is keyed to the cross feed screw. The rocking arm houses

a spring loaded pawl which is straight on one side and bevel on the other

side..

As the driving disc rotates, the connecting rod starts reciprocating and

the rocking arm rocks on the fulcrum. When the driving disc rotates through

half of the revolution in the clockwise direction, top part of the rocking arm

moves in clockwise direction and the pawl being slant on one side slips over

the teeth of the ratchet wheel imparting it no movement.

As the driving disc rotates through the other half, the top of the

rocking arm now moves in the anticlockwise direction and the straight side

of the pawl engages with the teeth of the ratchet wheel causing the wheel to

move in anticlockwise direction only. As the driving disc is connected to the

bull gear the table feed movement is effected when the bull gear or driving

disc rotates through half of the revolution i.e, during return stroke only.

Rotation through other half imparts no feed movements. To reverse

the direction of rotation of ratchet wheel and feed, a knob on the top of the

pawl after removing the pin is rotated through 180°.

The movement of feed may be altered by shifting the position of

crank pin w.r.t the centre. Greater the through the eccentricity more will be

the rocking movements of the arm and the pawl will pass through three or

four teeth on the ratchet wheel at a time imparting greater feed movement.


Page 72

Planning Machine

Chapter-5

The planner like a shaper is a machine tool to produce plane and flat

surfaces by a single point cutting tool

Difference between shaper & planner

The work is stationary; the tool along with ram reciprocates against the

work.

The work which is supported on the table reciprocates and the tool is

stationary.


Page 73

Principal parts of a planner:

BED:

� The bed of a planner is a box like casting cross ribs.

� It is a very large in size and heavy in weight and it supports the

column and all other moving parts of the machine.

� The guides ways are provided on the bed for the movement of the

table.

� The hollow space within the box like structure of the bed home the

driving mechanism for the table.

Table:

� The table supports the job and reciprocates along the ways of the

bed.

� The planner table is heavy rectangular casting and is made of cast

iron.

� The top face of the table is accurately finished in order to hold the

job correctly.

� The top face of the table is ‘T’ slotted for clamping the job and job

holding devices.

� At each end of the table or hollow space is left for collecti9ng chips.

� A groove is cut on the side of the table for clamping planner revising

dugs at different position.

MANUFAC

Column:

� It is a rigid ve

� The front fac

guide ways o

accommodati

� The housing

screws for to

rail.

CROSS RAIL:

� It is a rigid bo

� The cross rail

and can be cl

� The cross rail

surface of the


vertical box like structure.

face of each housing is accurately machines to

on which the crosier may be slipped up and

ating the different suitable heights job.

g is enclosed with vertical elevating screw and c

tool heads and counter balanced the weight of

box like casting connecting the two housings.

ail can be raised or lowered on the face of the hou

clamped at any desired position.

ail when clamped showed remain parallel to the to

he table.

Page 74

to provide

d down for

cross feed

of the cross

ousing

top


Page 75

� The two elevating screws in two the housing are rotated by an equal

horizontal any in position.

� The two tool heads are mounted upon the cross rail.

� The cross rail has screws for vertical and cross flew of the tool heads

and a screw for elevating the rail.

TOOL HEAD:

� The tool head of the planer is similar to that of a shaper in

construction and operation.

CLAMPING OF JOB:

� There are three important points to be hosted while clamping the job

on the planer table.

� The work should be connected rigidly to the table so that it may not

be shifted out of its position while cutting progresses.

� Proper clamping should be done all round the job.

� The job should be so held that the surface planed should remain in

proper position with other surface.

� The job may be located on the planning machine table by the

following methods.

� By standard clamping devices.

� By special fixtures.

� The standard clamping devices are t-bolts, stops, planer jacks, heavy

duty vises, angle plates & planner centres etc.

PLANER TOOLS:

� The cutting tools which are uses in planer are single point cutting

tool which are used in lathe and shaper.

� Planer tools may be solid for get type or bit type.

� The bit may be brazed, welded or mechanically held on a m.s bar.

� As a planer tool has to take up heavy cuts, the tools are made fevaier

and larger in cross section.


Page 76

Milling Machine

Chapter-6

Milling machine:

A milling m/c is a type of metal cutting device which remove metal

with a fast rotating multi-touch cutter.

As this m/c yield high production of different varities of jobs, in

choice for production m/c, comes after the lathe.

Generally smaller jobs are employed for machining in milling m/c. If larger

jobs are handled, then the m/c will perhaps be slower.


Page 77

Because of using multi tooth cutters & various forms of cutters, a

milling m/c can be economically employed for generating varties of surfaces

quite speedily.

Types of milling m/c:

Milling m/c are available in various basing covering a wide range of

work & capacities. The choice for a particular m/c depends on the nature &

size of the work to be undertaken.

a) Column & knee type. Milling m/c.

a. Hand milling m/c

b. Plain milling m/c

c. Universal milling m/c

d. Omniversal milling m/c

e. Vertical milling m/c

b) Manufacturing/ fixed bed type. Milling m/c

c) planer type milling m/c

d) Special type milling m/c.

a. Rotary table machine.

b. Drum milling m/c.

Milling attachment:

It is a rotary table types work holding device bolted on the table. It

provides a rotary motion to the w/p in addition to longitudinal, cross &

vertical motions.

Dividing head/indexing head:

Indexing is an operation of dividing a periphery of a cylindrical w/p

into equal no. Of divisions by the help of index crank & index plate.

Indexing is accomplished by using a special attachment known as

dividing head/indexing head.

Dividing heads are 3 types

1. Plain/simple dividing head:

2. Universal dividing head

3. Optical dividing head.

MANUFAC

Plain/ simple dividi

� It has

three j

� A wor

crank

index

� In a

horizo

� The in

horizo

� The i

perform


iding head:

as a spindle which carries job holdering device

e jaw chuck, face plate with centre carrier

orm wheel is rigidly fixed on spindle. While an

k is mounted on the worn shaft such that the ro

x crank finally results in the rotation of the spindl

plane dividing head, its spindle rotates onl

zontal axis.

index plate remains fixed & does not rotates on

zontal axis.

index plate remains fixed & does not rota

orming simple indexing operation.

Page 78

ces such as

an indexing

rotation of

dle.

nly around

only around

otate while


Page 79

The amount of the spindle relative to the worm depends on the ratio

between the relations of worm & the worm wheel.

The most common ratio is 40:1, which means 40 revolutions of index

crank or worm will move the worm wheel or spindle through one complete

revolution.

Universal dividing head:

� It is the most commonly used type of attachment on the

milling m/c.

� It is used for the following purposes.

� Setting the w/p in horizontal, vertical & inclined positions

relative to the milling m/c table.

� Turning the work periodically through a given angle per

forming indexing of the work.

� Imparting a continuous rotary motion to the w/p for milling

helical grooves.

� Dividing head spindle is connected with the table feed screw

through a gear train attachment to impart a continuous rotary

motion to the w/p for helical milling.

� Working mechanism of an universal dividing head is the crank

which is rigidly fixed at one end of the work shaft, while the

bevel gear runs free on the worm shaft.

� The index plate is bolted with gear & can be locked aginst the

rotation of lock pin.

Optical dividing head:

It is used for high precision angular indexing of the job with respect to

the cutter.

For reading the angle, on optical system is built into the dividing

head.

Spindle:

Spindle is located in the upper part of the column.

It gets driving power from motor to transmit it to the arbor.

The front end of the spindle just projects from the column face & is

provided with a tapered hole to accommodate various cutting tools & arbors.


Page 80

Arbour:

The arbor is connected with a spindle through a bolt, which serves as

an extension of the m/c spindle on which milling cutters are safely mounted

& rotated

It is taper shank for proper alignment with the spindle having tapered

hole at its nose.

Work holding devices:

Work holding device used on a milling m/c includes the following:

Vices which may be plain vice, swivel vice & tool maker’s universal vice.

� Angle plates.

� v-blocks

� special fixtures.

Work holding attachment:

Special attachments are used on miiling m/c for performing different

typical operations. Common attachments include:

a. Vertical milling attachment: used for facilitating the horizontal spindle

milling m/c to do facing on horizontal surface or for making grooves.

b. Universal milling attachment: similar to vertical attachment with

added features for swivelling the spindle about two mutually

perpendicular axis.

slitting attachment :

used for converting rotational motion of the horizontal spindle m/c

into up & down vertical reciprocating motions. The slotting head is fitted to

the spindle & is used for cutting slats. The attachment can be swivelled to

any angular positions.

high speed milling attachment:

it is a gearing system used for increasing the spindle speed by four

to six times. The attachment is bolted to the face of the column.


Page 81

Rack milling attachment:

It is bolted to the face of the column. Used for cutting rake teeth.

Differential Indexing :

Available no. Of index plates with different hole circles sometimes

limit the range of plate indexing. In such case differential indexing is found

useful. In this process, the indexing plate rotates itself in relation to the crank

during the process of indexing. For making necessary calculation to find the

change gears to be placed between the spindle and the power shaft use the

following relation

Where N = no. Of divisions to be indexed

N is a no. Of slightly or less than N. After simplification, the above

relation n will give the gear ratio between the gears to be placed on the

spindle (driver) and the own shaft (driver).

Gears may be arranged in a simple train or in a compound train as the

case may be.

When (n – N) is positive, the index plate must rotate in the direction

in which the crank is rotated.

If (n – N) is negative the index plate rotates in the opposite direction

to that of the crank.

Dividing head attachment:

A dividing head attachment is also a special work holding de3cvice

which is bolted on the machine plate. The work may be mounted on a chuck

fitted on the dividing head spindle or may be supported between alive or

dead centre.

The dead centre is mounted on a foot stock as in a lathe tail stock that

is bolted on the machine table after after correctly aligning its spindle axis

with the dividing heads. spindle


Page 82

Universal dividing head:

The attachment is similar to the vertical attachment but it has an added

arrangement for swivelling the spindle about two mutually perpendicular

axes. This feature of the attachment permits the cutting spindle axis to swivel

at practically any angle and machine any compound angle surface of the

work. The attachment is supported by the over-ram and operates at either the

same speed or at higher speed than the scope of machine.


Page 83

Slotter

Chapter-7

SLOTTER

It is used for cutting grooves, key ways and slots of various shapes

for making regular and irregular surfaces both internal and external.

Difference between slotter and shaper:

SLOTTER SHAPER

The ram holds the tool and reciprocates in a vertical axis

The ram holds the tool and reciprocates in a horizontal axis.

MANUFACTU

SLOTTING MACH

Base/bed:

The base of th

forces and entire loa

NUFACTURING TECHNOLOGY

CHINE PARTS:

f the machine is rigidly built to withstand all cuttin

oad of the machine.

Page 84

ting


Page 85

COLUMN:

� The column is the vertical member which is cast integral with the

base.

� Driving mechanism and feeding mechanism are inside the column.

� The front vertical face of column is accurately finished for providing

ways on which the ram reciprocates.

SADDLE:

� The saddle is mounted upon the guideways and may be moved

towards or away from the column either by power/ manual control to

supply longitudinal feed to the work.

� The top surface of the saddle is accurately finished to provide

guide ways for the cross slide.

� These guideways are perpendicular to the guide ways on the base.

CROSS SLIDE:

� The cross slide is mounted upon the guide ways of the saddle and

may be moved parallel to the face of the column. The movement of

the slide may be controlled either by head or power to supply cross

feed.

ROTATING TABLE:

� The rotating table is a circular table which is mounted on the top of

the cross slide. The table may be rotated by rotating a worn which

meshes with a worm gear connected to the underside of the table.

� In same machines the table is graduated in degrees that enable the

table to be rotated for indexing.

� T-slots are cut on the top face of the table for holding the work by

different clamping devices.

� The rotary table enables a circular or contoured surface to be

generated on the work piece.

RAM & TOOTHED ASSEMBLY:

� The ram is the reciprocating member of the machine mounted on the

guide ways of the column.

� It supports the tool at it’s bottomed on tool head.


Page 86

RAM DRIVE MECHANISM:

� A slotter removes metal during downward cutting stroke only whereas

during upward return stroke no metal is removed.

� To reduce the idler time quick return mechanism is incorporated in

the machine.

FEED MACHANISM:

� The teed is given by the table.

� A slotting machine table has 3 types of feed movements.

LONGITUDINAL:

� If the table is fed perpendicular to the column towards or away from

face the feed movement is termed as longitudinal.

CROSS: If the table is feed parallel to the face of the column the feed

movement is termed as cross.

CIRCULAR: If the table is rotated on a vertical axis the feed movement is

circular.

SLOTTER TOOLS:

� = top rake angle

� = from clearance angle

� In a slotter the pr. Acts along the length of the tool.

� In slotter tool the angles are provided for better cutting.

� The nose of the tool projects slightly beyond the shank to provide

clearance.

� The slotter tools are robust in cross section and usually of torged

type.

� Bit type tools are fitted in heavy duty tool holders.

� Key way cutting tools are thinner at the cutting edges.

� Round nose tools are used for machining circular/ contoured

surfaces.

� Square nosed tools are used for machining flat surfaces.


Page 87

Grinding

Chapter-8

Grinding M/C:

• Grinding is the process of removing material from work piece. The

removing of material from the W/P is either two end its diametre

within very closed tolerance (0.02mm) or to give a fine finish or the

work surface.

• The grinding machine supports and rotates the grinding wheel for

smooth operation. Grinding machine is used for roughing and

finishing flat, cylindrical and conical surface.


Page 88

• The grinding wheel is made of fine grains of abrasive materials. The

grains during the rotation of the wheels remove very small chip[s .

• As the selection of chips remove is very small and high cutting speed

are involved, the grinding operation results into a very good finish or

the work surface and high accuracy in work dimensions.

Types of Grinding:

Oftainly used to grind casting and weldments using portable grinders

or pedestal; grinder

Fine Grinding :

• It is applied for finishing of those materials which are too hard to be

machined by other methods of metal cutting.

• It is also used for producing surface on the job to attain higher

dimensional accuracy and finish

BED/BASE

• It is a heavy cast iron construction and support s other parts of the

slotting machine such as column, ram and its driving mechanism,

table etc.

• The top of the base is accurately finished to provide guide ways for

mounting of the saddle. The cross-slide guide ways are

perpendicular to the column face.

Column

• It is a vertical structure cast integral with the base.

• It houses the mechanism for driving ram and feeding mechanism.

• The front vertical face of the column carries guide ways for ram

to reciprocating upon it

Saddle:

• It is mounted upon guide ways and can be moved towards or away

from the column

• The saddle caries guide ways for cross-slide

• The feed is given by manual or power.


Page 89

Cross-slide:

• It is mounted upon guide ways made at the top of the saddle and

can be moved parallel to the front face of the column.

• Feed is given manual or by power.

• Table

• It is a circular rotary table mounted on the top of the cross-slide

• A circular feed handle for the table is provided

• Rotation of the table is effected by hand or by power

• The table carries T-slots to help mounting of jobs on the tabloe

• Ram and tool head

• They reciprocates up and down on the guide ways made on the front

face on the column.

• The ram carries a tool head at its bottom end.

• In some mechanism special tool head is provided to releave the tool

during its return stroke

• A quick return mechanism is given with the machine which enables

the return or ideal stroke to be completed faster than the cutting

stroke

Methods of grinding:

According to type surface to be grounded main kinds of grinding

methods are as follow:

External cylindrical grinding: produces a straight or tappered surface

on a w/p when it is rotated about its own axis between centers as it passes

lengthwise across the face of a revolving grinding wheel.

Internal cylindrical grinding: it produces internal cylindrical holes &

tapers. The work is chucked & rotated on its axis, while the grinding wheel

rotates against the work.

Surface grinding:

It produces flat surfaces & the work may be grounded either by

periphery or by end face of the grinding wheel.


Page 90

Face grinding:

It is a method of grinding vertical flat surface & the wheel spindle

may be vertical or horizontal.

From grinding:

It is done by specially shaped grinding wheels to grind formed

surfaces as gear teeth, threads, shaft, dovetails etc.

Set wheel grinding:

It is a method of grinding short w/p without changing the grinding

wheel.

Centre less grinding:

It is a method of grinding external & internal cylindrical surfaces in

which the work is supported among a regulating wheel, a grinding wheel &

a work rest blade.

Off-hand grinding:

It is rough grinding method in which work is held in hand and

pressed

Against the rotating grinding wheel. For example grinding a chisel

on pedestal grinder


Page 91

Types of grinding machine:

Grinding machine may be broadly classified as follows

1. Surface grinder

2. Cylindeical grinder

3. Center-less grinder

4. Portable grinder

5. Pedestal grinder

6. Cutter and tool grinder

7. Internal grinder

8. Flexible shaft grinder

Surface grinder :

a. It is used for grinding flat surfaces

b. Surface grinding effective for removing hard spots and sets

from the work surface

c. Surface grinding machine differs according the shape of

grinding wheel and motion given to the work table during

working.

d. Some common type surface grinding machine are prescribed

in the following

Horizontal spindle surface grinding machine:

It is used for the circumferemce of a straight grinding wheel and are

able to handle a wide range of work with super finish and externally fine

limits of accuracy

Vertical spindle flat grinding machine:

These are strongly built machine. They yield more out put with cup

type wheel rather than using of straight wheels.

Disc grinding machine:

These are used for rough semi precision grinding rapid removal of

metal is done by this type of machine.


Page 92

Internal Machining operations

Chapter-9

MANU

Introduction


Page 93

MANU


Page 94

MANU


Page 95

MANU


Page 96


Page 97

MANU


Page 98

MANU


Page 99

MANU


Page 100

MANU


Page 101

MANU


Page 102

MANU


Page 103

MANU


Page 104

MANU


Page 105


Page 106

Surface finish, lapping

Chapter-10

Introduction:

In a manufacturing plant, a product may be shaped, turned,

milled or drilled, and left in that condition as being satisfactory for use.

However, if a better finish is desired, for looks, for accuracy, for

wearing qualities, or for any other reasons, one of the micro finished

that include lapping, honing, super finishing, polishing, buffing, may

be employed. In some cases other operations are done only to get

durable finishes.


Page 107

LAPPING:

Lapping is an abrading process that is used to produce

geometrically true surfaces, correct minor surface imperfection,

improve dimensional accuracy, or provide a very close fit between two

contact surfaces. Very thin layers of metal (0.005 to 0.01mm)are

removed in lapping and it is therefore, evident that is unable to correct

substantial error in the form and size of surface, it is however low

efficiency process is used only when specified accuracy and surface

finish cannot be obtained by other method. Abrasive powders (floors

such as emery, corundum iron oxide, chromium oxide mixed with oil is

mixed with oil or special paste with some carrier are used in lapping.

Most lapping is done by means of lapping shoes or quills called

laps that are robbed against the work. The face of a lap becomes

‘charged’ with abrasive particle. Charging a lap means to embed the

abrasive grains into surface. Laps may be made of almost of any

material soft enough to receive and retain the abrasive grains. They are

made of soft iron, brass, copper, lead or soft steel.

The method of charging a lap depends upon the shape of lap.

When the lap is once charged it should be used without applying more

abrasive until it ceases to cut. Lap may be operated by hand or

machine, the motion being rotary or reciprocating.

Cylindrical work may be lapped by rotating the work in the lathe

or drill press and reciprocating the lap over the work in an ever-

changing path. Small flat surfaces may be lapped by holding the work

against a rotating disc, or the work may be moved by hand in an


Page 108

Irregular path over a stationary face plate lap. In equalizing lapping the

work and lap mutually improve each other surfaces as they slide on

each other.

There are three important types of lapping machines. The

vertical axis lapping machine laps flat or round surfaces between two

oppose laps on vertical spindle. The centre-less lapping machine is

designed for continuous production of round parts such as piston pins,

bearing races and cups, valve tappets and shafts.

The centre less lapping machine on the same principle as centre

less grinding. The abrasive belt lapping machine lapps bearings and

cam surfaces by means of abrasive coated clothes.

lecture notes - government polytechnic, nayagarh

Documents